We analyze the evolution of the international collaboration network in photovoltaic research. Using data on scientific publications for the period 1980-2015, we apply social network analysis to trace the evolution of the global network of countries and national research networks of...

Cluster policies are often intended and designed to promote interaction in R&D among colocated organisations, as local knowledge interactions are perceived to be underdeveloped. In contrast to the popularity of the policy measure little is known about its impact on knowledge networks, because...